Aircraft heating system



May Z1,V 1946. l s.' E. lx-naYlvArm 2,40,509

f AICRAFT 'HEATING SYSTEM I K y Filed Ot. 15, 1942 2 Sheets-Sheet l HEATER May 21,1946.

s. E. -HEYMANN Y AIRCRAFT HEATING SYSTEM Y Filed oct. 15, v1942 2 sheets-sheet 2 mnu,

' is a slight disadvantage in flowing to the engine A further object is Patented May 21 .1946

AuNrrlznf STATES l PATENT oFFflcE i 2,400,509 I` i y Seymour E. Heymann, Stewart-Warner Corporation,

corporation of Virginia Application October 15, 1942, Serial'No.

Chicago, Ill., a

claims. (Cl. 2314123 'l My invention relates generally to aircraft kheat-I ingv systems andl apparatus, and more particularly to control means therefor. l l

It has .become common practice to utilize a portion of the yi'uel and airmixturefsuppliedto thev aircraft engine by its supercharger as a source of combustible mixture for the operation of one or more internal combustion type heaters for heating the 4,cabin and other parts of the aircraft. The products ofcombustion from 'the heater have f ordinarily been discharged overboard, but in some instanoesfhave been'returned tothe inlet of the supercharger. Undersome conditions of opera# tion of theairplane, it isv desirable to utilize' the vdifferentialpressure between the inlet and the outlet ofthe supercharger to cause new ofthe combustible mixture to the heater and tocause -the discharge of the products; of combustion other conditions of op-v therefrom. while `under eration, ,thel pressure diierential between the' pressure side phere is sujmcient for satisfactory operation of the heater. i 4 i Y f yAlthough under/substantially all conditions of airplane operation, the kheater will'operate satisfactorily when it is connected between the outlet there and the inlet of the engine supercharger,

permanently connecting the heater inthis manner. lEventhough the 'products-of combustion entering .the inlet of the supercharger form but aV small percentage'of the flow through 'the of the mixture supplied to the enginestherefore does not noticeably aect'engine operation, such dilution must have some effect; and it is .therefore advisable to avoid such. admixture of theproductsthe heater with the charge l whenever possible. It is therefore anv objectof my invention to of combustion from provide improved `means v1f or automatically conl trolling the iiow of exhaust gases froman internal combustion type heater, either tothe atmosphere or to the inlet side of the engine supercharger,

depending upon the conditions under which the airplane is operating.

to provide an improvedfdiofthe supercharger'and the atmos supercharger, and the dilution .Y combustion from the'heater lli are withdrawn through a conduit )22 'leading to the inlet 23'of y an autonjiaticallyA operated three-way valvey 24.` This valve has tw'o' outletsZS and 26, the outletv 25 being connected by a mosphere, the conduit projecting through the skinl verter valve and Ioperating means therefor-for controlling the .discharge of an internal combustion type heater.

Other objects will appear from the following description, reference being had tothe accom panying drawings,inwhich: f

f with an anchoring bracket Fig. 1 is a diagrammatic viewv of a typicalheater l installation embodying the invention;

Fig. 2 is 'a central' longitudinal s'ec'tonal'view of the three-way diverter valve; and,

Fig. 3 is a side elevational view of said valve. As shown in Eig. 1, the heating system comprises an internal combustion type heater I0, which may be of any suitable construction, such,

lever `42.

which it jis shown in Conduit 21 with the at- 28 of the airplane,y preferably at a point at which thepressure is reducedv when the airplane is in flight.

The otheroutlet 26 of thethree-way'valve 24 yis .connected by a conduit with the induction the throttle valve 20 pipe I8 fat. a point between and the inlet ofthe supercharger I4, so as to be at al1 times subjected to thefull suction produced b`y the'superchar'ger. The threefway-valve 24 has its operation controlled bythe pressure within the conduit l2, a suitable conduit 32 connected between the three-way valve 24 andthe conduit |2 being providedl to transmit this controlling pressure to'thevalve. u

As best shown in Figs. 2 and 3',`the three-way valve 24 comprises an integral body casting having three bosses 'forming the inlet 23'and f outlets 25 and 26'. The body has a generally cylindrical borel. Secured to a shaft 361s a valve vane or disc 40 which fits snugly inthe cylinder 36." Fixedly secured-to the end of the shaft 38 and outsideof the body 34. is a three-armed Arms 44 and 45 of the lever 42 are adapted to 'engage Vstop lugs 46 and 41 formed on the body casting of the vane 40' from theposition in which the vane is shown in full linesfin Fig. 2 tothe positionin dotted linesin said figure. The arm 44 is connected `by a tension spring '48 n so as normally to bias the three-armed lever 42 and the vane 40 to the positions in which these parts are-shown in the drawings (thefull-line position of vane' A4&1). A tensionspring 52 has one end'connected tothe end of the third arm 54 of the three-armed lever 42, and its other'en'd anchored to a stud 56 projecting from the body 34.

The arm45 of the three-armed lever 42 is connected to a flexible diaphragm 58 by means of a rod 60' and 'anadjustable clevis 62.y The periphery of the diaphragm 58 is secured to ay peripheral edge of a diaphragm casing 64 by a folded seam. Y l

l v 34 to limitthe extent of oscillatory'movement'of the shaft 38, and hence that Whenever the pressure at theoutlet side of 5 the supercharger I4 is suiciently high for satisfactory operation of the heater utilizing the overboard discharge conduit 21, this high pressure will be exerted upon the diaphragm 58 and swing the which substantially the results of my invention may be obtainedV by the use of substantially the same or equivalent means.

I claim:

1. In a heating system for aircraft equipped with an engine supercharger, a hermetically sealed internal combustion type heater, means for conveying a combustible mixture from the pressure side of said supercharger to said heater, al-

valve vane 40 from its full-line to its dotted-line 10 ternatively utilized discharge conduits for conveyposition (Fig. 2). It will be apparent also that to accomplish such movement of the valve to the dotted-line position, the `pressure exerted upon/ the diaphragm 58 must be suflicient to overcome ingf'the products of combustion from the heater, either to the atmosphere or to the inlet of said supercharger, valve means for controlling the iiow through said discharge conduits, and means rethe tension of the spring 48 and, during the/initial 15 sponsive to the difference in pressure between portion of the movement, to overcome/the additional tension provided by the spring '52. During the latter portion of the movement of the lever 42, the spring 52 will assist/such movement, the spring 52 thus being eifective to cause quick snapover of the vane from one of its operating positions to the other operating position and prevent- 'ing the vane 40 /from being brought to rest in a median position'.

`When the valve is thus movedto the dotted-line position, itis arrested in this position by the engagement of the arm 44 with the lug 46, and the products of combustion from the heater `entering the inlet 24 will fiow through the upper portion of the valve cylinder 38 and from this cylinder through the outlet 25 and conduit 21 to the atmosphere.

Whenever, due to a change in the character of operation of an airplane engine, as by causing the engine to operate at full power, the pressure at the outlet of the supercharger I4 decreases, such decreased pressure will be reected upon the surface of the diaphragm 58` so that the spring 48 will be effective to return the valve 40 to its full-line position. When the valve 40 is in its full-line position, the products of combustion from the heater are cut off from flow to the atmosphere through the conduit 21 and are diverted to flow through the outlet 26 and conduit 30 into the induction pipe I8. Since, as previously stated, there-is always a difference in pressure between the inlet and. outlet of the supercharge I4 adequate to cause satisfactory operation of the heater I0, the heater will continue in operation' despite such considerable decrease in the pressure at which the combustible mixture is supplied to it.

The valve 24 is preferably located-so that the lower surface of its diaphragm 5,8 is subjected to atmospheric pressure. Thus it will be seen that the movement of the diaphragm 58, and hence the shifting of the valve 40, is responsive to the differential pressure between the pressure side of the supercharger I4 and the atmosphere, and that whenever. this pressure difference is not adequate ,for operation of the heater, thevalve is shifted to a position in which the heater exhaust is drawn into the low pressure side of the supercharger., which will at all times be at a subatmospheric pressure.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made therein Without departing from the underlying principles of 70 the invention. I therefore desire, bythe following claims, to include within the scope of my invention al1 such modifications and variations by the pressure side of said supercharger and the atmosphere for operating said valve means to cause the products of combustion to flow to the atmosphere through said discharge conduits whenever said pressure diiference exceeds a predetermined value, and operating said valve to cause flow ofthe products of'combustion from said heater to the inlet side of said supercharger whenever said pressure difference falls substantially .below said predetermined value.

2. 'I'he combination set forth in claim 1 in which said differential pressure responsive means comprises a diaphragm having one side thereof subjected to the pressure at the outlet of said supercharger and the other side thereof subjected to atmospheric pressure, and said valve means comprises a three-Way valve operated by said diaphragm.

3. The combination set forth in claim' l in which said valve means comprises a three-way valve, said pressure difference responsive means comprises a diaphragm having its opposite sides subjected respectively to atmospheric pressure and the pressure at the outlet of said supercharger, and in-which quick-snap-over mechanism is provided to cause complete and'rapid movement of said valve. i 4.' A control for` an aircraft heater of the in- F ternal combustion type supplied with combustible 4" mixture from a supercharger and adapted to exhaust alternatively through a tail pipe or through a pipe leading to the intake of the supercharger, /altWo-position valve controlling communication 50 between the exhaust of said heater and said alternative pipes, and motor mechanism for shifting said valve in response to differences in pressure between the fuel inlet of the heater and the atmosphere, said motor mechanism operating to move said valve rapidly between its rtwo operative positions and therebyto cause the exhaust of the heater to be discharged either to the atmosphere through said tail pipe or to Vthe intake of the supercharger. e

5. A control for an aircraft heater of the internal combustion type supplied with a combustiblemixture from the aircraft supercharger and adapted to exhaust either through a tail pipe or through a pipe leading to the intake of the supercharger, a valve for-controlling communication between the exhaust of said heater and said pipes, and motor mechanismoperable'in response to differences in pressure. between the fuel inlet of the heater and the atmosphere to shift said valve to connect the exhaust` of the heater either tosaid tail pipe or tothe intake of the supercharger. d

ySEYMOUR E. HEYMANN. 

